The present invention relates to a novel reaction product, to a pigment comprising the reaction product, to a process of producing same, to an electrophotographic photoconductor using such a reaction product, to an electrophotographic apparatus having such an electrophotographic photoconductor, and to a process cartridge for such an electrophotographic apparatus.
Conventionally, the photoconductive material for use in the electrophotographic process is roughly divided into two groups, that is, an inorganic photoconductive material and an organic photoconductive material. The above-mentioned electrophotographic process is one of the image forming processes, through which the surface of the photoconductor is charged uniformly in the dark to a predetermined polarity, for instance, by corona charge. The uniformly charged photoconductor is exposed to a light image to selectively dissipate the electric charge of the exposed area, so that a latent electrostatic image is formed on the photoconductor. The thus formed latent electrostatic image is developed into a visible image by use of a toner comprising a coloring agent such as a dye or pigment, and a polymeric material. Such an electrophotographic process is called xe2x80x9cCarlson processxe2x80x9d.
The photoconductor employing the organic photoconductive material is advantageous over that employing the inorganic photoconductive material with respect to the degree of freedom in the wave range of the light to be employed, and the film-forming properties, flexibility, transparency, productivity, toxicity, and manufacturing cost of the photoconductor. In light of the above-mentioned advantages, most of the current photoconductors employ the organic photoconductive material. The photoconductor which is repeatedly operated by the above-mentioned electrophotographic process or the like is required to exhibit excellent electrostatic properties, more specifically, excellent photosensitivity, acceptance potential, retentivity of charge, potential stability, residual potential and spectral sensitivity.
In recent years, the development of data processing apparatus employing the above-mentioned electrophotographic process is remarkable. In particular, there is a remarkable improvement in the printing quality and the reliability of the digital printer which is capable of recording data by digital recording method, to be more specific, converting the data into digital signals and recording the data using a light. Such a digital recording system is applied not only to the printer, but also to the copying machine. Thus, the digital copying machine is actively developed. It is supposed that the demand for the digital copying machine will further increase in line with the addition of various data processing functions.
The photoconductor designed for the above-mentioned digital recording system is required to have special characteristics which are different from those required for the conventional analogue recording system. For instance, semiconductor laser (LD) or light emitting diode (LED) is widely employed as a light source for the digital recording system because of its compactness, cheapness and high reliability. The wave range of the currently used LD is within the near infrared region, while the wavelength of the currently used LED is 650 nm or more. Therefore, the electrophotographic photoconductors for use with the above-mentioned digital recording system are required to show sufficient sensitivity in the wavelength range from the visible region to the near infrared region. In light of the above-mentioned sensitivity, a squarylium dye (Japanese Laid-Open Patent Applications 49-105536 and 58-21416), a triphenylamine trisazo pigment (Japanese Laid-Open Patent Application 61-151659), and a phthalocyanine pigment (Japanese Laid-Open Patent Applications 48-34189 and 57-14874) are proposed as the photoconductive materials for use in the digital recording.
In particular, the phthalocyanine pigment, that is, a titanyltetraazaporphyrin compound, can show absorption and photosensitivity in the relatively long wavelength range. In addition, a variety of phthalocyanine pigments can be obtained according to the kind of central metal or the type of crystalline form. Therefore, research and development of this type of phthalocyanine pigment has been actively conducted to obtain the improved photoconductive material for use with the digital recording. Examples of the conventional phthalocyanine pigments capable of showing good sensitivity include xcex5-type copper phthalocyanine, X-type metal-free phthalocyanine, xcfx84-type metal-free phthalacyanine, vanadyl phthalocyanine, and titanyl phthalocyanine. To be more specific, titanylphthalocyanine pigments with high sensitivity are proposed in Japanese Laid-Open Patent Applications 64-17066, 3-128973 and 5-98182. Those titanylphthalocyanine pigments exhibit maximum absorption in the wavelength range of 700 to 860 nm, so that they can show remarkably high sensitivity with respect to the semiconductor laser beam. It is also known to be effective for the purpose of obtaining phthalocyanine pigments with specific crystal structures to treat the phthalocyanine pigments with an acid, an organic solvent or water (Japanese Laid-Open Patent Applications 145550). Japanese Laid-Open Patent Applications Nos. 8-6050, 8-283599 and 2-269776 disclose a method of treating titanyl phthalocyanines with trihaloacetic acid.
However, when each of the above-mentioned titanylphthalocyanine pigments is employed in the electrophotographic photoconductor, there still remain a lot of practical problems, for example, decline in charging performance due to fatigue, and an increase in temperature- and humidity-dependence of the charging characteristics although the sensitivity is sufficient [Y. Fujimaki, Proc. ISandT""s 7th International Congress on Advances in Non-Impact Printing Technologies, 1,269 (1991); K. Daimon et al.; J. Imaging Sci. Technol., 40,249 (1996)].
With regard to other tetraazaporphyrin derivatives, Japanese Patent Publication No. 2-39160, 3-27111, 4-283581 and 4-113361 disclose that pigments with asymmetric scheletons or mixed pigments such as a mixture of a phthalocyanine with a phthalocyanine-nitrogen or phthalocyanine-sulfur analogue is effective as the photoconductive material.
When these pigments are used for an electrophotographic photoconductor, the sensitivity in the visible light and near infrared range, charging characteristics and resistance to repeated use are still unsatisfactory.
It is an object of the present invention to remove the drawbacks of the photoconductive material in the conventional electrophotographic photoconductors and to provide a novel reaction product useful as an organic photoconductive material for electrophotographic photoconductors, a process of producing such a reaction product, an electrophotographic photoconductor containing such a reaction product, an electrophotographic machine using such a photoconductor and a process cartridge for an electrophotographic machine.
The present inventors have made an earnest study with a view toward solving the above problems and have found that a crystalline reaction product capable of being obtained by reaction of (i) a nitrile derivative of the formula (1) shown below with (ii) a phthalonitrile derivative of the formula (2) shown below or a 1,3-diiminoisoindoline derivative of the formula (3) shown below and, if necessary, with (iii) a metal or a metal-containing compound shows excellent charge generating properties and excellent electrophotographic characteristics. The present invention is based on this finding.
In accordance with the present invention, there is provide a crystalline reaction product having charge generating properties and capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a phthalonitrile derivative of the general formula (2) shown below.
In accordance with the present invention, there is also provided a crystalline reaction product having charge generating properties and capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a phthalonitrile derivative of the general formula (2) below and with a metal or a metal compound.
In accordance with the present invention, there is further provided a crystalline reaction product having charge generating properties and capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a 1,3-diiminoisoindoline derivative of the formula (3) shown below.
In accordance with the present invention, there is further provided a crystalline reaction product having charge generating properties and capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a 1,3-diiminoisoindoline derivative of the formula (3) shown below and with a metal or a metal compound.
In accordance with the present invention, there is provided an amorphous reaction product capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a phthalonitrile derivative of the general formula (2) below.
In accordance with the present invention, there is further provided an amorphous reaction product capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a phthalonitrile derivative of the general formula (2) shown below and with a metal or a metal compound.
In accordance with the present invention, there is further provided an amorphous reaction product capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a 1,3-diiminoisoindoline derivative of the formula (3) shown below.
In accordance with the present invention, there is further provided an amorphous reaction product capable of being obtained by reacting a nitrile derivative of the general formula (1) shown below with a 1,3-diiminoisoindoline derivative of the formula (3) shown below and with a metal or a metal compound.
In accordance with the present invention, there is further provided a process for the production of a reaction product having a strong diffraction peak at a Bragg angle 2xcex8xc2x10.2xc2x0 of 27.2xc2x0 but having no diffraction peak at a Bragg angle 2xcex8xc2x10.2xc2x0 of in the range of 4xc2x0-10xc2x0 in a CuKxcex1 X-ray diffraction pattern thereof, characterized in that a reaction product having a strong diffraction peak at a Bragg angle 2xcex8xc2x10.2xc2x0 of 27.2xc2x0 and having weak diffraction peak at a Bragg angle 2xcex8xc2x10.2xc2x0 of in the range of 4xc2x0-10xc2x0 in a CuKxcex1 X-ray diffraction pattern thereof or the above amorphous reaction product is subjected to a crystal conversion treatment using at least one solvent selected from organic solvents, acids and water.
In accordance with the present invention, there is further provided a pigment characterized in that the pigment comprises the above crystalline reaction product having charge generating properties.
In accordance with the present invention, there is further provided an electrophotographic photoconductor comprising an electroconductive support and a photoconductive layer provided thereon, characterized in that the photoconductive layer comprises the above pigment.
In accordance with the present invention, there is further provided an electrophotographic machine comprising charging means, exposing means, developing means, transfer means, cleaning means, charge removing means and an electrophotographic photoconductor, characterized in that the above electrophotographic photoconductor is mounted as the electrophotographic photoconductor.
In accordance with the present invention, there is further provided a process cartridge for an electrophotographic machine comprising charging means and an electrophotographic photoconductor, characterized in that the above electrophotographic photoconductor is mounted as the electrophotographic photoconductor. 
In the above formulas (1)-(3), R1-R5 stand, independently from each other, for a hydrogen atom, a halogen atom, an aliphatic hydrocarbyl group which may have a substituent, an aromatic group which may have a substituent, a hydrocarbyloxy group which may have a substituent, a nitro group or a cyano group and n is an integer of 1 or 2, with the proviso that two of R2-R5 may link to each other to form a ring.